Treatment of viscose rayon with alpha-hydroxyadipaldehyde



2,728,628 TREATMENT OF VISCOSE RAYON WITH ALPHA- HYDROXYADIPALDEHYDE John P. Dosier, Ashevilie, N. C., assignor to American Enka Corporation, Enka, N. C., a corporation of Dela- Ware No Drawing. Application July 24, 1951, Serial No. 238,399 Claims. (Cl. 8-1164) The present invention relates to the treatment of cellulosic textile materials, and more particularly to a novel method for imp'roving the resistance to shrinking, or better said, the dimensional stability, wet strength and other properties thereof.

Fabrics that are woven, knit, or otherwise manufactured from cellulosic threads of regenerated cellulose are characterized by a pronounced shrinking upon repeated launderings. Moreover, these materials possess wet strengths that are appreciably lower than. the dry strengths. To overcome these undesirable characteristics, many methods have been proposed of treating either the thread or the fabric made therefrom.

In addition to the various improvements in dimensional stability and the wet properties obtained by these diiferent treatments there are often obtained improvements in such associated textile propertiesas crease-resistance, abrasionresistance, hand, and the like. The ideal treatment, of course, would afiect the desired results for all of these various attributes while not imparting anyundesirable after-effects upon the material. However, while some treatments give excellent results in one respect, they may actually impair other properties or impart to the material undesirable characteristics.

With respect to regenerated cellulose, especially when prepared by the viscose process, one of the most important problems is that of the dimensional stability. While it is known that a glyoxal treatment such as that described in U. S. Patent No. 2,436,076, can be used to advantage to render materials more resistant to shrinkage, there is an attendant loss in tenacity and a decrease in the wet and dry elongations. One explanation of this reduction in elongation is that the cross-links which are formed between the adjacent cellulose macromolecules are so short that the resulting structure is too rigid. It can thus be seen that while the glyoxal treatment is satisfactory for reducing the degree of shrinkage, it also produces an undesirable change in the physical properties of the fabric being treated.

It ,is therefore an object of this invention to provide an improved method for the treatment of cellulosic materials.

whereby the tendency of these materials to shrink upon wetting out is markedly reduced while at the same time the physical properties of the material thus treated are not impaired.

It is a specific object of this invention to treat cellulosic materials with a weakly acidic dilute solution of a long chain dialdehyde preferably having. four carbon atoms between the two terminal carbon atoms.

The manner in which these and other objects and features of the invention are attained will appear more fully from the following description.

The dialdehyde which is employed in the practice of this invention is first dissolved in an aqueous solvent to which is added 'a weakly ionizable organic acid, such as oxalic acid, to serve as a catalyst. The textile material of regenerated cellulose, in either filamentary or fabric form, is then treated by impregnating with this solution, drying at a temperature lower than the boiling point of water, and baking at a temperature above the boilingpoint of water.

nite States Patent (3 f 2,728,628 Patented Dec. 27, 1955 2 One satisfactory dialdehyde is a-hydroxyadipaldehyde, which can be represented as follows:

The solubility of the commercial form of this particular dialdehyde in water is not high enough to provide solutions of the order of 10%, but this difiiculty canbe overcome by using a solvent of about $4; water and dioxane.

The following examples will serve to illustrate the present invention:

Example 1 Five-hundred-yard skeins were hand reeled from an undried cake of washed but undried 150/ viscose rayon thread. Undried yarn was used for two reasons: (1) undried regenerated cellulose is still in the gel state and is more reactive than after drying, and (2) this would be a logical point of application for incorporation in the viscose process for the production of cakes.

A treating solution containing approximately 8% ahydroxyad'ipaldehyde and 0.6% oxalic acid (catalyst) was prepared by mixing 147 g. of a aqueous solution of a-hydroxyadipaldehyde with 300 ml. dioxane and diluting this to .a total volume .of 1000 ml. with water containing 6 g. oxalic acid as a catalyst. The dioxane prevented the precipitation of a white gummy material when diluting with water.

The moist skeins were soaked for 5 minutes in this treating solution at 50-60 C., centrifuged for 5 minutes, and dried for 1 hour at 50-55 C. The dried, treated skeins were then baked for the times and at the temperatures shown below, after which they were washed in a solution of 0.25% soap and 0.1% NazCOa at 70 C., rinsed until free from soap and alkali, dipped in a 1.0% emulsion of finish, again centrifuged, and finally dried 1 hour at 50-55 C. After conditioning, the skeins were transferred to spools and tested for dry and wet strength and elongation.

Results were as follows:

Baking Properties sample 'r Tl D w t: D amp. I118, ry e ry so. min. Strength Strength Elong. ll... w Control. Control- 177 92 21.7 I 30.4 4 199- 113 15. 0' 15,2 3 200 110 17.6 1s 2 Example 2 Skeins of viscose rayon yarn were treated in the same manner as described in Example 1 except that the concentrations of the a hydroxyadipaldehyde and the oxalic acid were varied as shown below. The baking treatment lasted for 3 min. at 120 C.

Results were-as follows:

Treating Solution Properties Oxalle 1) Wet Dry Wet Sample Aldehyde. Acid sa i. Str. Elong. .Elong.

0 0. 60- 58 14.6 13.4 3 0. 2a 189 97 17. 0 17. 9 4 0. 30 107 107 17. s 18. 0 0 0.45 203 100 16.8 10.4 s 0.60 206 114 16. a 10. 3 10 I 0.15 199 105 15.1 15.0

Example 3 l A series of skeins were treated in a manner similar q a to that of Example 2 except that a baking treatment of 4 min. at 110 C. was used. Results were as follows: I

Example 6 A series of skeins were treated as described in Example Treating Solution Properties 1 with an 8% solution of a-hydroxyadipaldehyde. The organic acid catalysts used wereoxalic acid, adi ic acid, 11 D w t W and succinic acid Samples were baked 4 minutes at x2. 0 e ry 'et a Sample Aldehyde Acid Str so. Elong. Elong. 110 c,

2 91 .11 a: 91 g V 12: s 11 Physical Properties 5 .1 we s 0.60 292 113 15.1 11.5 sample Catalyst PH 9 Dry Wet Wet 10 0.75 198 106 15.5 14.5 Sm EL EL "1'11" 1a at 92 0. oxa cac 86 A series of skeins were treated in a manner similar 15 ample 3 44 m 191 94 gm 2m to that of Example 1, except that a glyoxal treating og oaoigflfl 1 7 gs 36.6 a pcaci 9 7 .2 1.7 solution was used in compar1son w1th the ahydroxy 0.28% Succmic acid" m0 108 191 91 1M 2M adipaldehyde. These glyoxal solutions were prepared in 0.56% succinic acid" a 18 9a 197 101 19.5 22.7 accordance with the teachings of U. S. Patent No. 094% succmlc acid" 3 02 110 197 101 2,436,076, Examples 2, 4 and 6. Thus the three solu- 20 tions which were used contained 180, 120 and 90 ml./L

Example 7 of a glyoxal solution, which for convenience sake are designated A, B, and C, respectively. To afford a comparison between the baking conditions given for these particular solutions and the baking conditions utilized 25 with the a-hydroxyadipaldehyde treating solution, two skeins were baked for each of the glyoxal solutions. One was baked according to the specified conditions, while the second was baked at 115 for 3% minutes.

A cake of 150/ denier viscose rayon thread that had been thoroughly purified but not dried was used as a source of supply, from which short lengths of thread were withdrawn, passed through a treating solution, collected on a metal bobbin, and dried at 50 C.

Three separate treating solutions were used, (A) water, (B) an 8% solution of a-hydroxyadipaldehyde as de- Results are given in the following table: 30 scribed in Example 1, and (C) a solution of glyoxal, as

Treating Solution Baking Physical Properties Sample T! T Swelling D W t D W t me emp. I)? e W e Reagent Catalyst min. 0. s11. Str. Eiong. Eloug.

1 111 189 89 20.9 24.6 2 A-Glyoxal 2% gggfi gg a 19s 59 152 84 12.5 11.0 B-Glyoxal... .6 oxalic 110111.... 5 126 61 163 82 15. 2 14. 0 C-G1y0xa1 1.0% oxalic acid". 5 149 48 131 72 9. 1 9. 1 A-Glyoxal--- {$21 gggf gg x 31 5 11s 9a 184 87 19.3 18.2 B-Glyoxal... .6% oxalic acid 3% 115 110 184 87 19. 9 20. 5 C-Glyoxal 1.0% oxalic acid.-. 3% 116 102 186 86 19.8 20.8 8% adipaldehyde .6% oxalic acid 4 110 77 202 113 15. 1 14. 5

1 Control, not treated.

Example 5 specified in Example 4 of U. S. Patent No. 2,436,076,

A series of skeins were treated with a-hydroxyadipaldehyde in a manner similar to that of Example 1. For concentrations of 6% and 8% dialdehyde, skeins were treated with oxalic acid catalyst concentrations of 0.3, 0.6, and 1.0%. tions were used4 minutes at 110 C. and 3 minutes at 120 C.

in which 120 ml. of 30% glyoxal and 6 gm. of oxalic acid were added to 1000 ml. of water. a The treating solutions were maintained at C.

The dried yarn on the metal bobbin was then baked For each variation, two baking Candi. 50 at the conditions shown below, after which the physical properties and residual shrinkage were determined, with the following results:

Results were as follows:

Concentration Physical Properties Baking Physical Properties Shrink- Treat- Sample Dialde Cata Swell 89m ple ing 80- Dry Wet hyde, 11st, 2, i g? lution Time, Temp., Dry Wet El., EL, 5;; Percent Percent Percent min. degrees Str. Str. perpercent cent 1 (9 191 p 81 89 29.9 9.1 A 191 78 n 1 17 6 4 0 WITH 4 MIN. BAKING AT a 9 a a 19 92 as 21 o a 120 192 81 10.7 17.2 4 s s 0 98 195 97 19.0 21.9 o s 120 188 82 10.7 19.4 4 2 0 0. a 84 199 17. 0 10. o s 0.9 so 203 112 17.0 17.5 65 2 as a a: 12 it? a: 0 21 197 99 1010 1413 Example 8 s 1. 0 so 199 103 16. 2 15. 0

Skeins of 150/40 yarn were treated with an 8% solu- WITH 3 BAKING AT tion of a-hydroxyadipaldehyde, as described in Example 6 M 87 194 99 16 6 6 70 1. This yarn was knitted into a section of tubing be- 8 0.3 91 189 109 15.7 16.4 tween two sections of untreated normal yarn of the g 3 2 lg; lg? 2 E; samedenier. .An effort was made to knit a corresponds 1.0 so 122 14.8 13.4 ing section of tubing from yarn that had been treated 8 so 193 101 with glyoxal as described in Example 4, Sample 2, but

1 Control, not treated.

75 this latter yarn was too brittle to be knitted, and theresass-ass The treating solutions and baking conditions used on the swatches under b and d above, were:

Shrinkage Baking Sample g w (1th" Swatch Treating Solution T percent percent percent Time 2 81 Untreated. 2.2 17.5 25.0 T 4 Treated. 130 m5 1 Cglggtgiiegaggrgtafiglthwateronly l\0t;baked.

2 120 ml. 30% Glyoxal and 6 g. oxalic 5min 126 acid diluted to 1 liter with water. 3 147 g. 55% a-hydroxyadipaldehyde, 3.5 min. 115

6 g. oxalic acid, and 300 ml. dioxane Example 9 10111101 with water.

A comparison was made between an 8% solution of a-hydroxyadipaldehyde and a glyoxal solution, as described in. Example 2 of U. S. Patent No. 2,436,076, for After the final shmlkage measurements had been made, the property of reducing the Shrinkage of a woven duplicate breaking strength and total elongation tests fabric. The cloth employed was a Fuji-rayon having the made both h Warp and fillmg eacll h f u i characteristics; using test strips raveled to exactly one rnch 1n w1dth. Since these swatches had shrunk different amounts, they Construction 114 11V 68. had different thread counts and therefore inherently dif- Width 45%, ferent Strengths in addition to the possible chemical effect Warp 100/60 filament rayon. 5 of the aldehyde treatment. Each strength value was cor- Fillin (w ft) /1 spun rayon, rected forthe effect of the increase in the number of yarn ends due to shrinkage. On each swatch of cloth two concentric rectangles Results are given in Table II:

TABLE II Shrinkage (percent) Strength 3 Elong,

percent 3mm Treatment 15111 3511 2nd Wash 3rd Wash 4th Wash 5th Wash As Tested 5 3 BE S8 $B $R 18E 8EBK$ Water 17.4 4.0 20.4 16.7 4.7 20.0 10.7 4.4 20.2 18.6 4.7 23.2 18.0 5.0 223 51 5s 40 47 57 20 Glyoxal 0.0 3.1 12.7 10.4 2.8 12.0 10.4 2.8 12.9 12.0 3.1 14.8 10.7 3.2 13 s 43 41 42 37 33 24 a-Hydroxyadipal- 11.2 3.1 13.9 11.7 3.4 14.7 10.2 2.8 12.7 10.2 2.3 12.7 11.2. 3.4 142 40 4e 44 41 34 20 dehyde. I

Calculations based on the original dimensions. 2 Breaking strength inlbs.ior1 strip. Galen! ted tobasis 0! original cloth by corrcctlngior shrinkage.

were marked with a scour-proof textile ink. Each Example 10 swatch was then processed as follows:

(a) Washed by hand in a hot 0.25% soap solution, rinsed in hot water, and the excess water squeezed out, then (b) Soaked 15 min. in the treating solution at 70 C. and squeezed out by hand;

(0) The moist cloth stretched to its original dimensions on a drying frame and thoroughly dried at C.;

(d) The dry cloth removed from the frame and baked to set the aldehyde, then (e) Washed by hand in a hot (50 C.) solution containing 0.25% soap and 0.1% NazCOs, thoroughly rinsed in hot water, and dried relaxed under no tension on a horizontal wire screen. 1 a

(1) Finally, the shrunk, dried swatch was pressed (avoiding any sliding movement of the iron), and the reference area again measured to i at 10 points in each direction. The shrinkage after the first wash was then calculated.

The washing, drying and measuring, as listed under e and 1 above was repeated several times in order to detect any progressive shrinkage on repeated laundering.

A series of swatches were treated in a method similar to that of Example 9, except that:

1) The cloth was relaxed during the treatment in order to avoid any weakening of the fibers by the excessive tension which had been required to restore the wet fabric to the original dimensions.

(2) The cloth was hydroextracted after the aldehyde treatment, as had been done in yarn treatment. This was done so that the actual aldehyde content would be more comparable with that of treated yarn.

Results are given in the following table:

1 Corrected for the increase in the number at yarn ends due to shrinkage,

It can be seen from the foregoing examples that in the preferred form of this invention, the viscose rayon is treated with about an 8% solution a-hydroxyadipaldehyde. This is not intended to limit the scope of this invention to this particular compound, however, for it is contemplated to treat regenerated cellulose with other dialdehydes having four-carbon-atom chains between the terminal carbon atoms.

The mode of applying the dialdehyde to the material can be widely varied. It is particularly desirable to treat the filaments While they are still in the gel state, that is, before they have been dried once. Therefore, the process has particular utility in systems for the continuous manufacture of regenerated cellulose threads, e. g., in a system of the character described in application Serial No. 122,560 filed Oct. 20, 1949, assigned to the same assignee as the present application. In that system the dialdehyde solution can be used with optimum results in the last treating tube and prior to drying. However, this invention also finds applicability to the treatment of fabrics woven or knit from regenerated cellulose.

It has been found preferable to carry out the drying of the treated material at about 50 C. It is also preferable and economical to remove mechanically whatever excess treating liquid may remain on the material prior to this drying. The baking operation has been found to be most successful at l10120 C. at times of 3-4 minutes. Prolonged baking times or excessively elevated temperatures produce a reduction in strength, while insufcellulose, such as cuprammonium rayon, would be benefitted.

What is claimed is:

1. A process of improving the resistance to shrinkage, wet and dry strength and wet and dry elongation of viscose rayon which comprises treating the viscose rayon with an aqueous solution containing 4-1()% of a-hydroxyadipaldehyde and 03-12% of weakly ionizable, organic acid catalyst, drying the thus treated viscose rayon at a temperature lower than the boiling point of water, and baking the dried viscose rayon at a temperature above the boiling point of water.

2. The process of claim 1 in which the solution contains about 8% a-hydroxyadipaldehyde.

3. The process of claim 1 in which the organic acid catalyst in the treating solution is oxalic acid.

4. The process of claim '1 in which the organic acid catalyst in the treating solution is about 0.6% oxalic acid.

5. The process of claim 1 in which the treated viscose rayon is dried at a temperature of about 50 C.

6. The process of claim 1 in which the dried viscose rayon is baked at a temperature of ll0120 C. for about 3-4 minutes.

7. The method of improving the resistance to shrinkage, wet and dry strength and wet and dry elongation of viscose rayon which comprises treating the viscose rayon with an aqueous solution containing about 8% oc-hYClIOXY- adipaldehyde and 0.6% oxalic acid, drying at about 50 C., and baking at 1l0-120 C. for 3-4 minutes.

References Cited in the file of this patent UNITED STATES PATENTS 2,436,076 Pfelfer et al Feb. 17, 1948 2,548,455 Walker et al Apr. 10, 1951 FOREIGN PATENTS 317,085 Great Britain Dec. 8, 1930 547,846 Great Britain Sept. 5, 1942 

1. A PROCESS OF IMPROVING THE RESISTANCE TO SHRINKAGE, WET AND DRY STRENGTH AND WET AND DRY ELONGATION OF VISCOSE RAYON WHICH COMPRISES TREATING THE VISCOSE RAYON WITH AN AQUEOUS SOLUTION CONTAINING 4-10% OF A-HYDROXYADIPALDEHYDE AND 0.3-1.2% OF WEAKLY IONIZABLE, ORGANIC ACID CATALYST, DRYING THE THUS TREATED VISCOSE RAYON AT A TEMPERATURE LOWER THAN THE BOILING POINT OF WATER, AND BAKING THE DRIED VISCOSE RAYON AT A TEMPERATURE ABOVE THE BOILING POINT OF WATER. 